Spark-plug.



- tion of carbon,

--herein set forth.

CHARLES A. MARTIN, lor RACINE, wisconsin.

SPARK-PLUG.

. Specification of Letters Patent.

Patented Nov. 23, 1909.

Application led March 21, 1908. Serial No. 422,380.

To all whom it may concern: v

. Be it known that I, CHARLES A. MARTIN, residing in Racine, in the county of Racine andV State of Wisconsin, have invented Spark- Plugs, of which vthe following is a description, reference being had to the accompanying drawings, which are a part'of this speciication. l

My invention has relation to improvements in spark plugs.

The important object of the invention isV to provide a construction whereby accumulaoil, and other sediment in a plug, tending to create a short circuit and thereby preventing the jumping of `the spark, is guarded against.

A further object resides in providing for i the removability of the guard, whereby when it is Adesired to detach the guard for any purpose, as for instance, to substitutel for an old andvworn guard, a may be-readily accomplished.

With the above, and Vother incidental,- objects in view the invention consists of the devices and parts,

new one, this In the accompanying drawing, Figure 1 is a longitudinal vertical sectionalview of the complete device; Fig. 2 is a lower end view of Fig. 1; Fig. 3 is a view-of the lower end of Fig. 1 with the guard removed; Fig. 4 is a detail view of the guard; and Fig. 5 is a sectional View of Fig. 4.

Referring to the drawing, the numeral 6 1s provided at opposite ends with screw threads. The threads at the inner end are adapted to engage a threaded opening in the wall 7 of the engine cylinder, while the threads at the outer end are adapted to have a cap 8 turned thereon. Between its ends the casing is formed with an enlargement 9, preferably of hexagonal form for the applicationof a wrench thereto for the purpose of screwing the plug into 'or removing the same from the threaded opening of theI cylinder wall. y

The numeral 10 indicates an insulating tube which the cap 8 and enters the casing to such an extent that substantially one-half vof. the length` thereof is within the bore of the casing. At a point between its ends, the .in-

sulating tubeis provided with an enlarge' ment 11, said enlargement forming 'outer or their equivalents, as.

indicates the outer casing of the plug, which passes through an opening inand inner shoulders 12 and 13, respectively. The outer shoulder forms a seat for a packing 14, said packing being confined between the shoulder and the under side of the cap 8.

Passing through the bore of thev insulating tube is an electrical conductor 15 having its inner end pointed, as usual.' Between its ends the conductor is enlarged, as clearly shown in the drawing, to form an outer shoulder 16, and in order to accommodate this shoulder and to provide a shoulder to coperate therewith, the inner end of the bore of th'e insulating tube is also enlarged, the outer end ofA this enlarged portion of the bore forming a shoulder 1i' against which the shoulder 16 is adapted to be drawn.

The conductor 15 is adjustably clamped to..

the insulating tube by means of nuts 18, 18

the threaded outer end of said fact that the insulating tube becomes eX-` tremely hot when in use, I prefer that the .washers 19 be spring washers, so that yield-1' ing pressure'against the end of the insulating tube is provided, whereby the danger of cracking the heated porcelain of which the tube is4 composed, is considerably lessened.

Above the nuts 18 a binding nut 20 is turned on to the threads Interposed between the lower of:

of the conductor 15,

said binding nut adapted to clamp between itself and the u per one of the nuts 18 the electrical wire not shown) which runs to said electrical conductor 15.

The improved .form of guard employed by me is indicated by the numeral 2l. This guard is o-f conical form, the cone extending outwardly. At the apex of the cone the guard is 'formed with an orifice or small opening v22. The guard is suspended or held below the inner end of the casing G,

and by reason of the conical shape thercof,.

any carbon, oil, or other sediment, which may drop from the inner end of the casing onto the outer side of the cone is by reason of the slo ing walls of the cone shedV or discharged. RI carbon, or other Zmatter, 'which may accumulate on the inner side of the guard, inasmuch as the sloping formation thereof will necessarily cause the carbon or other mattei' to readily slide off or discharge.

A spark provision 1s made for preventing the accuhe'same is .true in regard to any' great disadvantage in many forms ofv plugs as now constructed 1s that no,

.y straight bottom.

mulation' of carbon,`oil etc., and hence hshort circuits are 'caused with a consequent interference with an eective jumping of 'the sparks. This ,isl particularly= true of those constructions wherein the innerend of the casing is formedwith a down 'ardly or inwardlyfpointing conical bottom, or with a Such formations of the bottoms of the .casings necessarily provide pockets or receptacles in which the clogging substances accumulate. construction of guard,`however, wherein the cone points -upwardly or outwardly, the

sloping walls lof the cone must necessarily outer ends of said arms being securedto the inner end'of the casing. Of course the arms could be rigidly secured, but I prefer that they be, connected so as to be readily.

detachable, whereby the guard is capable of being easily removed when necessary, as when it becomes yworn andA needsl to be replaced by a new guard. To accom lisli this, l bend outwardly the outer ends o the arms to forni laterally extending projections2t, 24, which projections are adapted to seat themselves upon an inwardly extending ledge or flange 25 formed at the inner end of the casing 6. This ledge or flange is y provided at diametrically oppositeT pointsy with recesses 26, 26. In order to attach the` guard, the arms 23 are pressed inwardly at theirv outer ends, and the lateral projections 24 are passed through the recesses 26. The

Aarms 'are then `permitted 'to spring outwardly, and by turning the guard the projections 2Lt'will rest or seat themselves upon the flange 25 of the casing, and be thereby heldin place Vhen it isdesired to remove or detach the guard, it isturned until the projections 24 are in registration with the order to clamp the guard in place, I provide an, linner sleeve 27, the outer end of said sleeve bearing against the inner shoulder 13 of'the` insulating tube, andthe inner end of said sleeve'bearing against the lateral projections 24 of the arms 23 of the guard.' It is obvious that when the cap 8 is turned i toward the cylinder of the engine the shoulder -13 is brought firmly against the outer' end of the sleeve 27, wh'ich of course willv causethe 'inner end of said sleeve to engage By my improved Atl this position, it is obvious thatthe guard may be readily withdrawn. In

firmly against the projections 24. The small opening or orifice 22` of the guard is .formed by planing or cutting off the' apex of the cone. This will necessarily make the bor-- `electrical conductor l5.

I prefer that the guard and its outwardly extending arms bev made of thin copper,

Copper, as is well understood, is of such nature as to become heated to a high degree.

This intense heat will therefore serve to assist in preventing the accumulation of carbon and other matter, inasmuch as it will serve -to burn od the said carbon or other matter. By this provision, therefore, even though the sloping wall of the cone does not shed off all the carbon and sediment, yet the heat emanating from the copper of which the guard is composed will burn any remainiiig carbon.

lt will be seen that I providea chamber 28 inthe inner end of the casing 6 of considerable area; A small quantity of gas from the engine cylinder enters this chamber, and this gas is first ignited by the spark. The explosion therefore which occurs in chamber 28 will create a draft in the direc- `tion of the cylinder, and this draft will also assist lin cleaning and quickly removing obstructions of carbon or other deposits;

What I claim as my invention is:

1. ln' a spark plug, the combination ofI an outer casing adapted to -be screwedinto the .cylinder wall of an engine, the inner end of said casing provided with an inwardly extending ledge or flange, said ledgeor flangeY -provided with recesses, A an insulating tube extending inwardly into the casing to a desired extent, a guard or defiector, the end thereof being in the form of airoutwardly extending cone and having the apex thereof pointing toward the casing andv apertured, the said end provided with arms extending toward the casing, the ends of the arms be- 'ing bent outwardly to forni lateral projections which are adapted to be passed through the recesses of theledge or lange of the cas-l ino; and to thereby detachablyengage abovev said ledge or flange, and an electrical con` ductor extending through the insulating tube, and having its inner end'in close proximity to the aperture.

2. In a spark plug, the combination of an outer casingadapted to be screwed into' the cylinderwall of an engine, the inner end of -said casing provided with an inwardly eX- tending ledge or flange, said ledge'or flange I provided with recesses, an' insulatingv tube extending inwardly into the casing to a desired extent, said tube formed withan enlargement between its ends tti-'provide outer and inner shoulders thereon, a guard or deiect'or, the end thereof `being in the form of an outwardly provided with arms extending toward the casing,"the' ends of the arms being bent to form Vlateral projections which are adapted to. lbepassed' through Ithe recesses ot the ledge'or fiange of the casing and to be thereby detachably engaged beyond said ledge or flange 2L- sleeve Within the casing, the outer end of said sleeve being .in .engagement with the inner shoulder of the insulating' tube, and the inner end of said sleeve engaging againstthe lateral projections at the ends of the arms of the guard, a nut turned on to the outer end. of the casing said nut provided with an opening through which the insulating tube passes, and said nut adapted to be-t-urned down against the outer shoulder-*ofthe insulatingtube, and an electricall conductor extending through the insulating tube and having its inner end 1n close prox- `imity t-o the spark orifice.`

3. In a spark plug, the combination of an outer casing adapted to be screwed into the cylinder Wall of'an engine, an insulating tube extending inwardly into the 4casing to a j extending cone, with a spark' `oriceat the apex of the cone, and said end desired extent, a removable open sided gua or defiector held.between the inner end of the casingy and the insulating tube, and the,

end thereof being in the form of an outwardly extending cone having the apex thereof pointing toward the casing and forming a` spark terminal, with a spark orice at the apex of the cone, and an electrical conductor extending through tir insulating tube and having its .inner end in close proxiinity to the -spark orifice of thev guard and forming the other spark terminal.

4. A guard or detiector for a. spark plug, having an open side and an end piece and provided with att-aching projections, the end piece being in the form of' an outwardly extending cone having the apex thereof pointino` toward the plug and being planed or out o to form both a spark orifice and a spark terminal hav-ing a. thin bordering edge.

In testimony whereof, I aix my signature, in presence of tivo Witnesses.

' CHARLES A. MARTIN.

Witnesses:

A. L. MoRsELL, ANNA F. SOHMIDTBAUER. 

